Check out this tech tip I wrote a few years ago. The title says "6 Volt" but the same principles and procedures will apply to the later model 12v systems.

https://www.stovebolt.com/techtips/6v_charge_system/index.htm

Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!